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editDynamics of super-rotation
editHide's Theorem, developed in 1969 by Raymond Hide, is the theoretical basis in understanding atmospheric super-rotation. The theorem states that eddies or waves must first cause disturbances in order for an atmosphere to develop super-rotation, thus making the role of atmospheric waves and instabilities crucial.[1] These dynamics, including Rossby waves and Kelvin waves, are integral in transferring momentum and energy within atmospheres, contributing to the maintenance of super-rotation. For instance, on Venus, the interaction of thermal tides with planetary-scale Rossby waves is thought to contribute significantly to its rapid super-rotational winds. Similarly, in Earth's atmosphere, Kelvin waves generate eastward along the equator, playing a vital role in phenomena like the El Niño-Southern Oscillation, demonstrating the broader implications of these dynamics in atmospheric science.[2][3]
There are three classes of super-rotating planets, each with different driving mechanisms: fast-rotating gas giants, slow-rotating terrestrial planets, and tidally locked planets.[4] For gas giants like Jupiter and Saturn, the quick rotational period causes strong Coriolis effects in the atmosphere. This results in strong atmospheric eddies that can efficiently transport angular momentum to the atmosphere, causing super-rotation.[2]
For slow rotating terrestrial bodies like Venus and Titan, super-rotation is often spontaneously initiated by Rossby-Kelvin (RK) instability. This instability comes interactions of equatorial Kelvin waves with high-latitude Rossby waves, causing momentum to converge at the equator and facilitate super-rotation.[4][5] Thermal tides caused by uneven heating are also responsible for super-rotation on especially slow rotating planets, namely Venus. These tides have been found to enhance super-rotation near the cloud tops by providing additional momentum toward the equator.[6][7]
Tidally locked planets are thought to initiate super-rotation through Matsuno-Gill patterns.[4] These patterns arise from strong asymmetry in heating between the day and night sides of tidally locked planets, which creates the vertical transport mechanism needed to transfer momentum from stationary eddies to the equator.[8] Matsuno-Gill patterns and RK instability are very similar mechanisms, and there had been work to unify the super-rotation mechanisms of slow-rotating planets and tidally-locked planets to create better understanding of the super-rotation in general.[4]
Venus: Extreme super-rotation
editThe atmosphere of Venus is a prominent case of extreme super-rotation; the Venusian atmosphere circles the planet in just four Earth days, much faster than Venus' sidereal day of 243 Earth days.[9] Wind speed hits a maximum of about 100 m/s at the top of the cloud layer 60 to 70 km above the surface, rotating about 50 times faster than the surface.[2] Zonal wind speed decreases both above and below this altitude, approaching near zero around 95 km.[2] This wind speed makes Venus the most extreme example of super-rotation in our solar system.
The initial observations of Venus' super rotation were Earth-based. The Venera missions in the late 1960s provided the first direct evidence of super-rotation through doppler tracking of the probe's descent.[6] Mariner 10 provided the first UV images of Venus' clouds, which enabled cloud tracking to measure the atmosphere's rotational period.[10] The Pioneer Venus multiprobes, Venera 9 and 10 landers, and Vega 1 and 2 balloons built vertical profiles of wind speed through the 1970s and 80s.[6][10] The Venus Express mission gave the first long-term monitoring of Venus' super-rotation, monitoring the cloud tops for 6 Earth years. Over the course of the mission, wind speeds increased from 300 km/hr to 400 km//hr, providing the first evidence that super-rotation is a changing dynamic system.[11] The latest mission, Akatsuki, produced over 4 million cloud-tracking measurements across almost 10 years. Akatsuki data has been used to refine super-rotation mechanisms, showing that thermal tides are the primary mechanism maintaining super-rotation on Venus.[12]
Modern general circulation models (GCM) are used to consolidate our knowledge of super-rotation and are used to simulate and test theories about the mechanisms and dynamics of super-rotation. One of the earliest mechanisms for the super-rotation of Venus was the Gierasch-Rassow-Williams (GRW) mechanism.[3] Early GCMs were based on this mechanism, but failed to match with observation data. Including thermal forcing in the GCM models in the 2010s has led to relatively successful models in recent years, and may be realistic enough to begin data assimilation projects from the Venus Express and Akatsuki missions databases.[3]
GCMs and observations are often enhanced by looking at past ancient climates. In a model where Venus is assumed to have an atmospheric mass similar to Earth, subsolar-antisolar circulation could have dominated over super-rotation in an ancient thinner atmosphere.[13]
References
edit- ↑ Lewis, Neil; Read, Peter (2021-03-03). "Planetary and atmospheric properties leading to strong super-rotation in terrestrial atmospheres studied with a semi-grey GCM". doi:10.5194/egusphere-egu21-4855. Retrieved 2026-05-04.
{{cite web}}: CS1 maint: unflagged free DOI (link) - 1 2 3 4 Imamura, Takeshi; Mitchell, Jonathan; Lebonnois, Sebastien; Kaspi, Yohai; Showman, Adam P.; Korablev, Oleg (2020-07-01). "Superrotation in Planetary Atmospheres". Space Science Reviews. 216 (5): 87. Bibcode:2020SSRv..216...87I. doi:10.1007/s11214-020-00703-9. ISSN 1572-9672.
- 1 2 3 Read, Peter L.; Lebonnois, Sebastien (2018-05-30). "Superrotation on Venus, on Titan, and Elsewhere". Annual Review of Earth and Planetary Sciences. 46: 175–202. Bibcode:2018AREPS..46..175R. doi:10.1146/annurev-earth-082517-010137. ISSN 0084-6597.
- 1 2 3 4 Nicolas, Quentin; Vallis, Geoffrey K. (2025-10-24). "Mechanisms of Superrotation in Slowly-Rotating and Tidally-Locked Planets". arXiv.org. doi:10.48550/arXiv.2510.21680. Retrieved 2026-05-04.
- ↑ Wang, Peng; Mitchell, Jonathan L. (2014-06-28). "Planetary ageostrophic instability leads to superrotation". Geophysical Research Letters. 41 (12): 4118–4126. doi:10.1002/2014GL060345. ISSN 0094-8276.
- 1 2 3 Sánchez-Lavega, Agustín; Lebonnois, Sebastien; Imamura, Takeshi; Read, Peter; Luz, David (2017-11-01). "The Atmospheric Dynamics of Venus". Space Science Reviews. 212 (3): 1541–1616. doi:10.1007/s11214-017-0389-x. ISSN 1572-9672.
- ↑ Lai, Dexin; Lebonnois, Sebastien; Li, Tao (2025-10). "Contribution of Thermal Tides to Venus Upper Cloud‐Layer Superrotation". AGU Advances. 6 (5). doi:10.1029/2025AV001880. ISSN 2576-604X.
{{cite journal}}: Check date values in:|date=(help) - ↑ Showman, Adam P.; Polvani, Lorenzo M. (2010-09). "The Matsuno‐Gill model and equatorial superrotation". Geophysical Research Letters. 37 (18). doi:10.1029/2010GL044343. ISSN 0094-8276.
{{cite journal}}: Check date values in:|date=(help) - ↑ "ESA Science & Technology - Major Discoveries by Venus Express: 2006-2014". sci.esa.int. Retrieved 2020-01-21.
- 1 2 Moissl, R.; Khatuntsev, I.; Limaye, S. S.; Titov, D. V.; Markiewicz, W. J.; Ignatiev, N. I.; Roatsch, T.; Matz, K.‐D.; Jaumann, R.; Almeida, M.; Portyankina, G.; Behnke, T.; Hviid, S. F. (2009-05). "Venus cloud top winds from tracking UV features in Venus Monitoring Camera images". Journal of Geophysical Research: Planets. 114 (E5). doi:10.1029/2008JE003117. ISSN 0148-0227.
{{cite journal}}: Check date values in:|date=(help) - ↑ Khatuntsev, I. V.; Patsaeva, M. V.; Titov, D. V.; Ignatiev, N. I.; Turin, A. V.; Limaye, S. S.; Markiewicz, W. J.; Almeida, M.; Roatsch, Th.; Moissl, R. (2013-09-01). "Cloud level winds from the Venus Express Monitoring Camera imaging". Icarus. 226 (1): 140–158. doi:10.1016/j.icarus.2013.05.018. ISSN 0019-1035.
- ↑ Horinouchi, Takeshi; Hayashi, Yoshi-Yuki; Watanabe, Shigeto; Yamada, Manabu; Yamazaki, Atsushi; Kouyama, Toru; Taguchi, Makoto; Fukuhara, Tetsuya; Takagi, Masahiro; Ogohara, Kazunori; Murakami, Shin-ya; Peralta, Javier; Limaye, Sanjay S.; Imamura, Takeshi; Nakamura, Masato (2020-04-24). "How waves and turbulence maintain the super-rotation of Venus' atmosphere". Science. 368 (6489): 405–409. doi:10.1126/science.aaz4439. ISSN 0036-8075.
- ↑ Yang, Jun; Boué, Gwenaël; Fabrycky, Daniel C.; Abbot, Dorian S. (2014-04-25). "Strong Dependence of the Inner Edge of the Habitable Zone on Planetary Rotation Rate". The Astrophysical Journal. 787 (1): L2. arXiv:1404.4992. Bibcode:2014ApJ...787L...2Y. doi:10.1088/2041-8205/787/1/L2. ISSN 2041-8205.